The relative burden
due to non communicable diseases (NCD) is increasing worldwide and has been
shown to be generally greater for men than women. The objective of this paper
is to describe gender differences in NCD mortality rates and trends in Brazil.
Standardized mortality rates for the years 1991-2010 were corrected for sub
notification and ill defined causes of death and calculated using sex specific
five year age grades. Trends in standardized mortality were studied using joinpoint
regression models. In 2010, rates for NCDs (men: 479/100000; women: 333/100000)
and for most major NCD categories (cardiovascular diseases, cancer, chronic
respiratory diseases and other chronic diseases) were higher for men than women.
Age standardized mortality rates declined for both sexes over the period, beginning
in 1993 and attenuating in more recent years. From its peak in 1993 to 2010,
the unconditional probability of dying between the ages of 30 and 70 due to
one of the four principal NCD groupings decreased for men from 32.3% to 22.8%;
for women, from 23.5% to 15.4%. In conclusion, age standardized NCD mortality,
though decreasing dramatically over the past two decades in Brazil, remains
notably greater in men than in women and, this difference, in relative terms,
will increase if these trends continue.

Key words: Chronic
disease, Brazil, Mortality, Sex

Introduction

The burden due
to non-communicable diseases (NCDs) is increasing world-wide, posing a great
threat to the development of the nations1,2. If current tendencies
continue, a recent study estimates that the cost of NCD to the world´s
economies over the next two decades could reach US$47 trillion; and for Brazil,
the annual cost could reach 4% of the gross national product3. These
global challenges, with particular reference to the low- and middle-income countries,
have been widely discussed in recent years, culminating with the High-Level
meeting of Heads of State held at the United Nations in September, 20114.

Brazil has developed
a strategic plan to deal with the NCD burden5. The main lines of
the plan are based on the Action Plan developed by the World Health Organization
(WHO)6. Attention is focused on four main groups of diseases (cardiovascular,
cancer, chronic respiratory and diabetes). As an indicator to measure the progress
towards the established goals related to mortality from NCD, the WHO has proposed
using the unconditional probability of a premature death due to these four groups,
defined as occurring between the ages 30 and 707.

In Brazil NCD mortality
is below that estimated in 2008 for most low income countries, but greater than
that estimated for high income countries and also most Latin American countries8.
A clear decline in NCD mortality has been observed when examining age-adjusted
trends. The decline started in the 1990´s and persisted up to now, although
at a lower rate in more recent years9. To be able to compare these
rates over time and across groups, these mortality analyses took into account
corrections for sub notification and ill-defined causes of death.

Notably, little
information is available regarding gender inequalities in NCDs mortality and
trends. From the WHO site, estimates indicate an almost uniformly greater mortality
due to NCDs across nations8. The objective of this paper is to describe
gender differences in mortality trends due to NCDs in Brazil. Additionally,
given the importance of developing heath indicators for NCD prevention globally,
we will estimate also, separately by sex, the unconditional probability of dying
due to the four main NCD between ages 30 and 70, which is likely to be the indicator
to be used in the years to follow.

Methods

Records of mortality
were obtained from the Ministry of Health mortality information system (SIM;
Sistema de Informação sobre Mortalidade). In this system causes
of death are recorded according to the ICD-9 codes from 1991-1995 and to ICD-10
codes from 1996 until the present. The codes were divided into the major disease
groups according to the WHO scheme10.

SIM became a computer-based
system in 1979 and covers the whole of the national territory. The quality of
the recorded information has improved consistently over the years, both from
the point of view of coverage as well as the proportion of deaths due to ill-defined
causes. In order to make valid comparisons across the years, the numbers of
registered NCD deaths were corrected for sub-notification and ill-defined causes.

A mixed approach
to estimate mortality system coverage was used. For 1991 a model life-table
separated by 5-year age-groups (with 80+ being the final open ended group),
regions and sexes furnished by the IBGE was used11. Data obtained
from field-work carried out for the year 200812 provided empirically-based
estimates of coverage for the years 2000-2010, with a single estimate for each
state for each year applied to both sexes and to all age-grades. For the years
1992-1999 values were obtained using a linear interpolation between estimates
for the year 1991 and those for the year 2000.

Differently from
previous analyses13 the model life-table regional value generated
correction factors (equal to the ratio of expected/observed deaths) for sub
notification at the state rather than the regional level. Since only one sub
notification correction factor value was available for each of the states for
the year 2000, the values available for each state for 1991 in 34 strata (17
age-grades x 2 sexes) are converged to this one value. When the correction factor
is greater than 1 (number of estimated deaths was greater than those observed),
a corrected number of deaths was obtained multiplying the observed number by
this correction factor ratio.

The deaths due
to ill-defined causes were redistributed to the other disease categories using
the methodology proposed by Mathers et al.10 This assumes that the
ill-defined causes of death may be divided in the same proportions as those
due to natural, non-external, causes. Thus, for each year and for each strata
defined by sex, state, and age-grade, the number of deaths due to natural causes
was modified by multiplying it by the following formula:

(t-e)/((t-e)-d)

where

t is the total
number of deaths in the strata,

e is the number
of deaths in the strata due to external causes, and

d is the number
of ill-defined deaths in the strata.

This correction
was not applied to deaths due to external causes.

Mortality rates
were calculated per 100.000 inhabitants. The population figures, furnished by
IBGE, were obtained from the DATASUS site. For the years 1991, 2000 and 2010
the numbers of residents are derived from censuses. For the year 1996 the numbers
are based on the IBGE population count. Linear interpolation, done at the strata
level, was used to obtain the values for the intervening years.

The mortality rates
were calculated for each sex-specific five-year age-grade, with 80+ being the
final open ended group. The rates were then standardized according to the direct
method using the WHO standard population14. Trends in mortality rates
were analyzed by joinpoint regression models using the Joinpoint Software, available
from the National Cancer Institute15. Models are fit to the data
so as to allow for testing of whether an apparent change in trend is statistically
significant. The trend is computed in segments whose start and end are determined
to best fit the data. These segments are connected together at "joinpoints"16.

The unconditional
probability of death due to the four disease groups cardiovascular disease,
cancer, chronic respiratory disease and diabetes was obtained using a formula
provided by the WHO. The first step consists in calculating the mortality rates
for each five year interval:

The usual demographic
practice of turning this rate into a probability was followed using the following
formula:

The individual
probabilities are then combined with the following formula to obtain an estimate
for the interval as a whole:

This is the statistic
which is then interpreted to be the unconditional probability of death between
the ages of 30 and 70.

The analyses described
in this paper are part of a project approved by the Hospital das Clínicas
de Porto Alegre Ethics Committee.

Results

In the year 2010,
a total of 1,132,732 deaths were recorded, 646,069 (57.0%) for men and 486,663
(43%) for women (Table 1). Of the total
number of the men, 409,484 (63.3%) had an NCD as a basic cause of death. Of
the total number of the women, 362,100 (74.4%) had a NCD as a basic cause of
death. After correction for sub notification and for ill defined causes of death,
a total of 1,209,676 records were available. Table
1 also shows the proportional mortality for groups of diseases in 2010 for
men and women, before and after correction for sub notification and ill defined
causes of death.

The remaining results
will always be presented with correction for sub notification and ill defined
causes of death. For women, 80.2% of all deaths were due to NCD, while for men
this percentage was 69.0%. The main reason for the difference is the higher
proportion of external causes of death observed for men (18.2 vs. 5.0%). Considering
NCD, for men and women, the main causes of death were cardiovascular diseases
(28.8% men, 34.4% women) and cancer (15.8% men, 17.8% women). The percentages
for chronic respiratory disease are 5.9% men, 6.2% women; and for diabetes 4.1%
men, 6.9% women. The percentages for other chronic diseases are 14.5% men and
14.9% women.

Tables
2 and 3 complement these numbers, showing
NCD and total deaths and the mortality rates separately by sex for the years
1991-2010. In 1991 the total number of deaths was 1,049,229; 675756 (73.8%)
were due to NCDs, 367530 (54.4%) among men and 308226 (45.6%) among women. In
2000 the total number of deaths was 1,047,365; 751,859 (71.8%) were due to NCDs,
407,395 (54.2%) among men and 344,464 (45.8%) among women.

It can also be
seen from Tables 2 and 3
that between 1991 and 2010 the population of men increased 29% (from 72,485,122
to 93,406,990) and the total of NCD deaths for men increased 30% (from 367,530
to 477,175). For women the population increase was 31% (from 74,340,353 to 97,348,809)
and the total of NCD deaths for women increased 35% (from 308,226, to 416,131).

The proportional
mortality for men and women increased steadily from 1991 to 2010. The crude
NCD mortality rate did not change significantly during this period (507/100.000
to 511/100.000) for men and (415/100.000 to 427/100.000) for women. The crude
rate peaked in 1993 for both men and women.

Nevertheless after
the direct age standardization, the mortality rate for both sexes underwent
a steady decline during this period: 28% for men (from 838/100.000 to 601/100.000);
and 33% for women (615/100.000 to 409/100.000).

An analysis of
these trends using joinpoint regression models shows (Figure
1) that, although points of inflexion were somewhat different for men and
women, for both the decline began in 1993 and was greater in earlier than in
more recent years. The latest observable trends were an annual decline for men
of 0.79%, and for women, of 1.0%.

Figure
2 shows that rates for most categories cardiovascular diseases, cancer,
chronic respiratory diseases and other NCD are higher for men than for women.
For both sexes the most important decline over the period occurred with cardiovascular
disease. The predominance of cardiovascular disease in these graphs masks the
fact that important falls occurred with chronic respiratory disease after 1998
(men) and 1996 (women).

Figure
3 shows the probability of dying due to the main causes of NCD death at
ages 30 to 70 years for men and women. A joinpoint analysis shows that for men
the probability of death from 1993 to present date has declined by 2.08% per
year. For women the decline from 1994 to 2006 was 2.77% per year but at present
it is 1.62% per year. When both sexes are combined, the decline from 2006 to
the present is 1.54% per year.

Discussion

Little has been
done to estimate gender inequalities in NCD mortality, particularly in low or
middle income countries. Our results clearly show that NCD is the main cause
of death for both men and women. The crude NCD mortality rate did not change
significantly between 1991 and 2010 for men (507/100.000 to 511/100,000) and
(415/100,000 to 427/100,000) for women. However, important declines in age-standardized
NCD mortality were seen during this period for men (28%, from 838/100.000 to
601/100.000) and for women (33%, 615/100.000 to 409/100.000). (Figure
1) The inflection points identified in the joinpoint analyses indicate that
the rate of decline is diminishing across the period, for both men and women.
These findings are similar to those previously reported9,17 using
slightly different methodologies for correction for sub notification.

Notably, age-standardized
NCD mortality rates were always higher for men than for women, except for diabetes.
In 1991, the ratio of mortality rates in men and women was 1.36 and, by 2010,
this had increased to 1.47. The World Health Organization reports mortality
rates from NCD for men and women around the world8. The ratio of
these rates in men and women is generally between 1 and 2. Very few countries,
mainly very small ones, have rates less than 1, and a few countries, mostly
those belonging to the former Soviet Union, have rates greater than 2.

Why are NCD rates
higher in men than in women? Empirically, the two main causes of death are cardiovascular
and cancer; and we found both to be higher in men (Figure
2). The most common cause of cancer death, men and women combined, is lung
cancer, mortality rates from which are approximately double in men compared
to women18. This is consistent with the greater prevalence of smoking
in men over the last decades19.

In Brazil, similar
increased overall mortality rates have been described for men from 1980 to 2005,
and the same was noted for preventable causes of death20. Notably,
higher rates of mortality, in men than women, which have been recorded for centuries21.

The global challenge
faced by the rising burden of NCDs is enormous. As has been emphasized by WHO1,2,
the burden will always be more unfavorable to countries and peoples with fewer
resources. Understanding and confronting the observed gender inequality is also
of paramount importance in meeting the challenge. In Brazil, in 2010, the unconditional
probability of dying from the four main categories of NCD between the ages 30
to 70 years is about 22.8% for men and 15.4 % for women. Further investigation
is warranted regarding possible explanations for differential mortality. Are
they related to higher risk factors in men (smoking, alcohol drinking)? Are
they a result of greater occupational exposures? Could they be due to less chronic
medical treatment (blood pressure, diabetes and cholesterol control)? Could
they be caused by delayed diagnosis and treatment of fatal condition such as
acute myocardial infarction, stroke and cancer?

Although corrections
for sub notification and ill defined cause of death will continue to be necessary
in analyses of mortality in Brazil, this should become less important over time,
assuming that current improvements in both coverage and quality of death coding
will continue. However, to permit analysis of past trends we will always need
to rely on some type of correction. Thus, improvements in our understanding
of the declines may benefit from further refinement in methods. For example,
the estimation of coverage using the model life table approach in 1991 might
be reviewed. Additional investigation of current rates of sub notification may
improve current estimates of the decline. Nevertheless, the joinpoint analysis
here presented indicates that declines have lessened in recent years.

In conclusion,
NCD mortality is considerably higher in men than in women, despite the declines
observed for both over the last two decades. This scenario, coupled with the
greater risk of external causes of death in men, forecasts an increasingly greater
gender differential in premature mortality. This is a remarkable challenge to
overcome.

Collaborations

A Stevens, MI Schmidt
and BB Duncan participated in the design, analyses and interpretation. A Stevens
created the computational system for the analyses.